… despite having been shot a little too early (or late) for the painting. (The “verticals” of the “bollards” and the verticals of the wall corners should be parallel.) It’s only … I guess less than a quarter-hour discrepancy, but it’s there.
Ah, there’s a change in the surface’s camber. That complicates matters.

I had first-hand experience of something like these when I slammed on my brakes at high speed to avoid taking out my vehicle’s undercarriage by a faux cattle guard that had been painted across a Montana highway.

It’s a good question.
Given the cost advantages (I’ve had a non-virtual cattle grid pole break under me – they do rust and require regular maintenance), I’m slightly surprised I’ve never seen one in Britain. Or maybe British livestock simply see past the illusion.
It’s a good question.

More frequent. But since there are no structural considerations to the paint … it could go either way.
The commonest way of building them in the UK is to rest scaffold poles on brick piers across the floor of the pit. So, the piers need adequate foundations ; the bricks are probably adequate for their compressive loads ; but the poles suffer bending loads depending on where the vehicle crosses. After a few years, the galvanizing on the poles can look fine, but the pole collapse under the weight of a person stepping on them. At which point the land-owner has potentially a significant liability problem. (In my case, I felt it going, so suffered no more than surprise, and told the farmer about it over a pint in T’Brass Cat that evening. But he still needed to fix it.)

Here they quite often seem to use old railway rails. Which are of course much stronger in bending than tubes (scaffold poles) and probably weather rust better too.

Besides, paint loses its effectiveness when covered in a layer of mud, and never works on gravel roads.

What they do use, quite often, are strips of woven fabric about 6″ wide laid across the road, incorporating wires and hooked up to an electric fence machine. The cows know not to step on it. They could very easily step over it but presumably they’re too dumb to figure that out. (Pigs would though).